Inhibitory Effect of Vegetables, Fruits and Herbs on .ALPHA.-Glucosidase in an Immobilized Enzyme Assay System

Abstract

A system using immobilized enzyme according to Oki et al., [Biol. Pharm. Bull. ,-(3) +*2.ῌ+*21 (,***)], which mimics the small intestinal membrane, was applied to the screening of several kinds of vegetables, fruits and herbs in terms of their inhibitory e#ects on a-glucosidase (AGH). AGH was partially purified from hog intestinal membrane by salting out, followed by immobilization on CNBr-activated Sepharose .B as a matrix. As substrate, p-nitrophenyl-aD -glucopyranoside (PNPG) was employed, producing p-nitrophenol (p-NP) by enzymic hydrolysis. Seven vegetables (Japanese radish, cabbage, onion, Chinese cabbage, tomato, cucumber, and carrot), / fruits (mandarin, apple, watermelon, melon, and grapefruit) and. herbs (Italian parsley, rucola, mache, and dill) were subjected to evaluations of the inhibitory e#ect on AGH. All of the test samples exerted an inhibitory e#ect on immobilized AGH (iAGH). Raw Chinese cabbage and boiled tomato among vegetables, mandarin among fruits and dill among herbs exerted the strongest inhibitory e#ect on iAGH.

Development of a bioassay-coupled HPLC-SPE-ttNMR platform for identification of α-glucosidase inhibitors in apple peel (Malus × domestica Borkh.)

“…Several studies have shown a-glucosidase inhibitory activity in various herbs, vegetables and fruits (Kawada, Miura, & Gomyo, 2006;Koga, Shibata, Yoshino, & Nomoto, 2006). However, the identification of active compounds in complex plant extracts is very time-consuming.…”

Evaluation of Herbal Foods on .ALPHA.-Glucosidase Activity and Glycemic Index

“…In our previous study, the inhibitory activities (IC 50 ) of raw herbal samples from dill, Italian parsley, corn salad and rocket were 115, 73, 71, and 28 mg/mL, respectively (Kawada et al, 2006). In the present study, the inhibitory effects of lyophilized samples were a 43-to 111-fold more than those of raw samples, suggesting that AGH inhibitory agents are concentrated in the lyophilized samples.…”

“…Partial purification of AGH AGH was partially purified from hog small intestine according to Kawada et al (2006). Briefly, fresh small intestine (1 kg) was scraped with the edge of scissors to obtain the mucous membrane.…”

“…Measurement of inhibitory effects on AGH Inhibition of AGH activity was measured as described previously (Kawada et al, 2006).…”

“…We have previously demonstrated the AGH inhibitory effects and the glycemic index (GI) of several spices and herbs (Nasu et al, 2005;Kawada et al, 2006). In the present study, we evaluated the effects of raw and lyophilized herbal samples and herbal tea on AGH inhibition and the GI to determine their possible clinical applications.…”